Film composer David Lang on the months he spent watching The Exorcist and learning how avant-garde music could transform a movie.

I had two jobs my senior year in high school—a music-related job and a film-related job. All these years later, both are on my mind, since I have been spending time in Los Angeles helping to promote Paolo Sorrentino’s new film Youth, for which I wrote the music.

I live in New York, but I grew up in Los Angeles, in Westwood, which is the neighborhood that surrounds UCLA. These days Westwood is a kind of anonymous shopping district, but in 1973, when I worked there, it still felt like a college town. It was a little bit like Berkeley or Ann Arbor, Michigan, with a democratic mix of used bookstores and nice restaurants and head shops and cheap pizza. At 16, I needed cash to upgrade my student trombone to a professional model, so I started looking for a job. Soon I had two: I’d parlayed my experience as a record-collecting classical music nerd into a position at a record store called the Warehouse, and with a friend’s help landed as an usher at the National movie theater just two bocks away.

David Lang.

Courtesy of Axel Dupeux

The record store only had room for me to stock a small selection of new classical releases, but it had a giant remainder section that would fill up with wild, obscure things I had never heard of before. All the major labels released adventurous recordings of new music; when these LPs stopped selling, they would get remaindered. The remainder bin was my university. Stockhausen’s Gruppenon Deutsche Grammophon’s “Avantegarde” series. Berio’s Circleson the Time label, whose releases were all spectacularly curated by composer Earle Brown. Nonesuch’s Golden Rain, my first experience with music from Bali, actually my first experience with world music from anywhere. I discovered all these in the remainder bin, selling for 25 cents apiece.

The discovery that changed me the most was the young Steve Reich’s first LP, on Columbia Records. I had no idea who he was, but I loved the cover, a cartoon of a violin in a rainstorm. I bought it. It was, after all, only 25 cents. I was completely unprepared for how radical this music was—Violin Phase, which on first listen was just a riff repeating over and over, and It’s Gonna Rain, which was made out of recordings of a street preacher’s voice overlapping and colliding with themselves. I was immediately hooked, and in pursuit of more LPs I soon found John Cage, La Monte Young, and Terry Riley. I found the young Philip Glass, whose self-produced records, on the Chatham Square label, were only available through the mail-order catalogues that I sent away for and pored over religiously. I bought them all. Weird music started to rule my life, and, oddly enough, it intersected with my other job as well.

It turned out that the National was one of Los Angeles’ most prestigious venues, where lots of movies would premiere. The klieg lights would park in front, the limos would pull up, and the stars would pour out of them. For a few hours we would be enveloped in the glitz and glamor of Hollywood. We had the first run in L.A. of The Godfather Part II. I got to watch every gunshot, every blood spatter, every heart-wrenching swell of Nino Rota’s amazing music, hundreds of times.

But the highlight of my time at the National was the premiere of the movie The Exorcist. We were the first and, for a time, the only movie theater in the world to show it, and people drove in from as far away as Las Vegas and Phoenix, hoping to get a ticket. We’ve all seen a lot of scary movies since 1973 so it can be hard to remember just how revolutionary The Exorcist was. For most movies my job was to take tickets, or help people find their seats, or stop the occasional smoker from lighting up in the theater; at The Exorcist, after each tense moment, the smokers would light up like crazy, and I spent much of my time at work trying to stop them. At least once a day someone would run into the lobby and throw up. It was virtuosically terrifying moviemaking, for audiences not yet used to being this terrified.

As I watched the film’s remarkable opening, I thrilled at the way the music—tiny, irregularly pulsing, super-high violins, like fingernails scraping across a blackboard— amplified the excitement and terror already in the theater. But the new-music lover inside me also perked up: Isn’t that the middle section of Penderecki’s String Quartet? Didn’t I just buy that, remaindered, for 25 cents?

William Friedkin’s original plan was to have the legendary composer Lalo Schifrin score the movie. According to an interview that Schifrin gave in 2005, the music he wrote for The Exorcist was deemed to be too terrifying. (You can hear some of his bristling and powerful score on the collector’s edition CD, and it is genuinely scary.) So Friedkin went a different direction, using music that already existed, almost all of it very recent music by living classical composers. There was George Crumb’s landmark anti–Vietnam War string quartet Black Angels. There was the first piece I ever heard by Hans Werner Henze, who would become my teacher 10 years later. Plus a concentrated dose of Penderecki. These were important composers I was just becoming aware of, and here they all were. Even Mike Oldfield’s Tubular Bells, the film’s ostensible “theme music,” felt hip and minimal, of a piece with the other music in the movie.

I saw The Exorcist a few hundred times. Eventually it began to hit me. Much of this music, when played in a concert hall, could push mainstream classical audiences away, but in a movie theater the audience accepted it. The music was a powerful part of the experience, in a way that made it inseparable from the visuals. The audience needed it. I have thought about that a lot over the years, that a big part of what makes music work is the context you put it in, the other senses and disciplines it collaborates with. I have been trying to put my music in the proper context ever since.

One of the beautiful things about writing the music for Youth is the context that Paolo created for it. He needed the music to be the doorway into the emotional life of Michael Caine’s character, to be part of the narrative. The retired conductor Caine plays would use words to communicate with other people but would use music to communicate with himself, so it was always clear to me what I was supposed to do. The candy wrappers, the cows, the scoring, the song at the end of the film— everything I wrote tried to make the music-making and the filmmaking one. That was a lesson I began to learn more than 40 years ago in the National theater in Westwood.

Correction, Dec. 9, 2015: The author biography of this piece originally misstated that David Lang composed the score for Requiem for a Dream. He arranged it for the Kronos Quartet; Clint Mansell was the composer.